The present invention relates to a wheelchair including a seat assembly having an upright leg member which telescopes into and out of an intermediate rear frame member in a substantially vertical manner. The seat assembly also includes a back member which maintains a substantially constant angle with respect to a vertical direction during telescoping of the upright leg member.
The invention pertains to wheelchairs, and more particularly, to a wheelchair seat having a changeable angle between a seat back and seat bottom or rail member. Although the angle therebetween is changeable, during adjustment of the seat bottom, the seat back member substantially maintains a constant vertical angle.
Prior art structures utilize a multitude of complex designs and configurations. Although some such arrangements have been commercialized, the industry still seeks a compact, reliable, simple and economical seat assembly.
U.S. Pat. No. 5,997,021 relates to an adjustable seat back assembly for a wheelchair of the type having a frame with an upwardly extending rear frame portion and an adjustable angle seat support which includes a pivotable front end and a rear end which is secured to said rear frame portion at any of a plurality of different positions. A seat back support is mounted to a pivot on the seat support from adjacent its rear end. A link connects the seat support to a slider on the rear frame portion to maintain the position of the slider relative to the seat back support pivot as the seat angle is adjusted. A releasable seat back angle adjuster secures the seat back support to the slider at any of a plurality of positions. When the seat back angle adjuster is released, the seat back support may be folded down towards said seat support.
U.S. Pat. No. 5,851,018 relates to a lightweight wheelchair having adjustable wheel camber, adjustable toe-in/toe-out positions, and front-to-rear adjustment of the wheel assembly relative to the frame. The wheel camber is changed by removable camber tubes having plugs in opposite ends with different angular relationships. The camber tube is removed from an axle tube, related through one hundred eight degrees, and reinserted to change the wheel camber. The location of the angular recesses in the camber plugs addresses minor toe-in/toe-out adjustments while rotation of an axle tube provided with indicia assures that proper toe-in/toe-out adjustment is provided for larger wheel camber adjustments. The front to rear location of the wheels relative to the frame can be adjusted via a single fastener on each side. Moreover, the track width of the rear wheels can be adjusted in response to the change in wheel camber.
Wheelchair users often have different preferences or prescribed requirements for comfortable or proper positioning in a chair. In order to meet these needs, a wheelchair is provided having a seating assembly including a back member and a bottom member with the angle therebetween being adjustable. The seating assembly is designed so that the back member substantially maintains a constant angle with respect to vertical while the angle between the back member and bottom member is adjusted as the seat bottom is lowered.
By maintaining the back member at a constant angle, the user""s center of gravity stays substantially the same, and is not allowed to move rearward upon lowering the rear of the seat, or forward upon raising of the seat, or vice versa. Another advantage of the seating assembly of the present invention is that stability and anti-tip forces are maintained even though the seating assembly is adjustable to numerous different positions. That is, if the angle of the back member were allowed to vary substantially upon lowering or raising of the chair, the wheelchair would have a greater likelihood of tipping.
Both the back member and bottom or rail member are operably connected to a seat bracket. Attached to the seat bracket is an upright leg member which telescopes downwardly into an intermediate rear frame member in order to change the angle of the seating assembly. Through independent adjustment, the angle of the back member with respect to vertical can also be adjusted.
Therefore, it is an object of the present invention to provide a wheelchair with a simple, quickly adjustable seat assembly.